Conveyor Sorting System – Guided Documentation

Objective

Design and build a system that:

• Moves a conveyor using a stepper motor
• Detects object color using a sensor
• Sorts objects into boxes using servo motors

1. System Overview

Think about the system in three parts:

Motion System

A stepper motor continuously moves the conveyor

Sensing System

A color sensor reads RGB values

Action System

Servos push objects into the correct bin

Your task is to connect these parts logically.

2. Stepper Motor (Provided – Study Carefully)

Pin Definitions

#define STEP_PIN 3
#define DIR_PIN 4
#define ENABLE_PIN 6

STEP_PIN sends pulses to move the motor.
DIR_PIN controls direction.
ENABLE_PIN turns the driver on or off.

Question: Why might the motor driver require an enable pin?

Basic Step Function

void stepMotor() {
  digitalWrite(STEP_PIN, HIGH);
  delayMicroseconds(stepDelay);
  digitalWrite(STEP_PIN, LOW);
  delayMicroseconds(stepDelay);
}

One HIGH to LOW pulse equals one step.
The delay controls how fast steps happen.

Key Idea:

• Smaller delay → faster motion
• Larger delay → slower motion

Question: What happens if the delay is too small?

Moving a Specific Distance

void moveToBox(float revolutions) {
  long stepsToTake = revolutions * stepsPerRev;

  for (long i = 0; i < stepsToTake; i++) {
    stepMotor();
  }
}

The motor moves in steps, not distance units.
We convert revolutions into steps.

Key Idea:

• stepsPerRev = steps in one full rotation
• revolutions = how far to move

Question: Why use revolutions instead of raw steps?

Stepper Setup

pinMode(STEP_PIN, OUTPUT);
pinMode(DIR_PIN, OUTPUT);
pinMode(ENABLE_PIN, OUTPUT);

digitalWrite(ENABLE_PIN, LOW);
digitalWrite(DIR_PIN, HIGH);

Pins must be outputs.
ENABLE is often active LOW.
Direction controls movement orientation.

Try: Change direction and observe behavior.

How the Stepper Is Used

The motor moves continuously using stepMotor().
When a color is detected, moveToBox() moves to a sorting position.

Question: What happens while moveToBox() is running?

3. Color Detection Logic (You Design This)

The sensor provides:

• Red (r)
• Green (g)
• Blue (b)
• Light (l)

Your task is to classify colors using comparisons.

Hints:

• Compare which value is largest
• Use differences between values
• Consider light level

Questions:

• Why is largest value alone unreliable?
• How does lighting affect readings?

4. Servo Control (You Implement This)

Each servo should:

• Start in a resting position
• Move to push an object
• Return to resting position

Hints:

• Use angles such as 0 and 180
• Add delay to allow movement

Questions:

• Why is delay necessary?
• What happens if it returns too quickly?

5. Main Loop Logic (You Build This)

Your loop should:

1. Move the conveyor slightly
2. Check for color detection
3. If detected:
   • Identify color
   • Move to position
   • Activate servo

Key Idea: The conveyor runs continuously until action is needed.

Question: Should the conveyor stop during sorting?

6. Integration Thinking

Consider:

• What is the motor doing while pushing?
• How do you ensure correct positioning?
• How do you adjust for lighting changes?

7. Testing and Adjustment

• Adjust motor speed (step delay)
• Print sensor values
• Tune movement distances

8. Extension Challenge

Add another color:

• How will you detect it?
• Where will the box be?
• How will the motor reach it?

Final Thought

This system combines continuous motion, sensing, and mechanical action. Focus on how these parts interact, not just how they work individually.